The Illustration above shows an
illustration of a Room & Pillar Mine. Room and pillar mining is
still very common in underground coal mines, because it is very flexible and does
not require a large capital expenditure for equipment like a longwall
mining operation would.
Room & Pillar is so named, because pillars of coal are left standing to
help support the roof of the mine. A typical design would have the entry ways
( or rooms) with a width of 20 feet, and the pillars with width's of 40-60 feet.
In some room & pillar mines, on retreat mining, the pillars are removed, allowing
the roof to collapse. This is called "pulling the pillars".

While a longwall section would have production rates of 1,000 to 20,000
tons per shift, room and pillar mines have lower production rates of
600 to 1,000 tons per shift per miner unit.

Photo is a Continuous Miner machine, commonly used in coal room and pillar mining. These
miners can achieve production rates up to 1,000 tons per shift. The
rotating bits on the drum rip the coal from the seam and it is gathered by rotating arms and
transported to a haulage vehicle by a chain conveyor.